Growth Hormone Withdrawal Research Articles

RF21 | PSAT93 Improvement of Final Height in Congenital Adrenal Hyperplasia Patients Treated With Recombinant Growth Hormone

Abstract Final height (FH) in congenital adrenal hyperplasia (CAH) patients is frequently under -1.5 SDS in relation to the normal population, even in those with good compliance, chronic androgen exposure or supraphysiological glucocorticoid doses could corroborate to this finding. Recombinant human growth hormone (GH) has been used as adjuvant therapy to improve FH in many disorders, but there are scarce data in CAH patients. Objective to analyze the effect of GH therapy on final height of CAH patients with compromised height prediction. Patients and Methods data of 26 patients (7F/19M) were retrospectively evaluated: 10 salt wasting-SW, 11 simple virilizing-SV and 5 with nonclassical form-NC. The SW patients were diagnosed at the neonatal period, SV and NC patients at mean chronological age of 3.6±2 and 7.2±3.8 yrs, respectively. All patients received cortisone acetate, hydrocortisone equivalent dose of 12.6±6.6 mg/m2/day in classical and 8.24±4.7 mg/m2/day in NC form; SW patients also received fludrocortisone 36±9.6mcg/m2/day. Near final height (NFH) was considered as BA of 13yrs for girls and 15yrs for boys; height and target height (TH) were described as SDS. All patients presented hormonal/molecular CAH diagnosis. The t test was used in the statistical analysis. Results Mean chronological and bone age (BA) at the beginning of GH therapy was 9.0±2.4 and 12.3±2yrs, respectively, mean duration of GH therapy was 4.1±1.9yrs and daily dose was 0.15 UI/kg/day. All patients were submitted to pubertal blockage with leuprorelin acetate 11.25 mg each 3 months during 3.9±1.1yrs or cyproterone acetate, mean dose 70±19 mg/m2/d during 4.7±2.5yrs. At the last evaluation, 19 patients (14M/5F) achieved FH: at the beginning of GH therapy mean H/BA in males was -2.1±0.38 and after -0.65±1 SDS (p<0.001). Mean FH in males was 165.7±5.9 cm and mean TH 170.7±8 cm (p>0.05); the TH-FH was -0.6±1.2 SDS. Among females, mean H/BA at the beginning of GH therapy was -2.2±0.7 and after -0.84±0.9 SDS (p=0.01). Mean FH in females was 156±8 cm, mean TH was 160±5.8cm (p>0.05); the TH-FH was -0.6±0.7 SDS. Considering patients with FH and NFH, the FH-TH in males was 0.4±0.2 SDS and -0.15±0.9 SDS in females. An improvement of approximately 12.7cm in males and 12.4cm in females was observed. No patient presented hypertension and 7/26 patients presented insulin resistance, which normalized after GH withdrawal. Conclusion we observed that GH therapy associated with puberty blockers allowed the achievement of final height in the expected range of target height, without significant side effects. Presentation: Saturday, June 11, 2022 1:00 p.m. - 3:00 p.m., Sunday, June 12, 2022 1:00 p.m. - 1:05 p.m.

Role of growth hormone in hepatic and intestinal triglyceride-rich lipoprotein metabolism

Elevated plasma concentrations of hepatic- and intestinally-derived triglyceride-rich lipoproteins (TRL) are implicated in the pathogenesis of atherosclerotic cardiovascular disease and all-cause mortality. Excess of TRL is the driving cause of atherogenic dyslipidemia commonly occurring in insulin-resistant individuals such as patients with obesity, type 2 diabetes and metabolic syndrome. Interestingly, growth hormone (GH)-deficient individuals display similar atherogenic dyslipidemia, suggesting an important role of GH and GH deficiency in the regulation of TRL metabolism. We aimed to examine the direct and/or indirect role of GH on TRL metabolism. We investigated the effect on fasting and postprandial hepatic-TRL and intestinal-TRL metabolism of short-term (one month) withdrawal of GH in 10 GH-deficient adults. After GH withdrawal, we found a reduction in fasting plasma TRL concentration (significant decrease in TRL-TG, TRL-cholesterol, TRL-apoB-100, TRL-apoC-III and TRL-apoC-II) but not in postprandial TRL response. This reduction was due to fewer fasting TRL particles without a change in TG per particle and was not accompanied by a change in postprandial TRL-apoB-48 response. Individual reductions in TRL correlated strongly with increases in insulin sensitivity and decreases in TRL-apoC-III. In this relatively short term 'loss of function' human experimental model, we have shown an unanticipated reduction of hepatic-TRL particles despite increase in total body fat mass and reduction in lean mass. These findings contrast with the atherogenic dyslipidemia previously described in chronic GH deficient states, providing a new perspective for the role of GH in lipoprotein metabolism.

Mammary Tumors Growing in the Absence of Growth Hormone Are More Sensitive to Doxorubicin Than Wild-Type Tumors.

Previously, we reported that N-methyl-N-nitrosourea (MNU)-induced mammary tumors could be established in mutant spontaneous dwarf rats (SDRs), which lack endogenous growth hormone (GH) by supplementing with exogenous GH, and almost all such tumors regressed upon GH withdrawal. When the highly inbred SDR line was outcrossed to wild-type (WT) Sprague-Dawley rats, MNU-induced mammary tumors could still be established in resulting outbred SDRs by supplementing with exogenous GH. However, unlike tumors in inbred SDRs, 65% of mammary tumors established in outbred SDRs continued growth after GH withdrawal. We further tested whether these tumors were more sensitive to doxorubicin than their WT counterparts. To accomplish this, MNU-induced mammary tumors were established in WT rats and in SDRs supplemented with exogenous GH. Once mammary tumors reached 1 cm3 in size, exogenous GH was withdrawn from SDRs, and the subset that harbored tumors that continued or resumed growth in the absence of GH were selected for doxorubicin treatment. Doxorubicin was then administered in 6 injections over 2 weeks at 2.5 mg/kg or 1.25 mg/kg for both the WT and SDR groups. The SDR mammary tumors that had been growing in the absence of GH regressed at both doxorubicin doses while WT tumors continued to grow robustly. The regression of SDR mammary tumors treated with 1.25 mg/kg doxorubicin was accompanied by reduced proliferation and dramatically higher apoptosis relative to the WT mammary tumors treated with 1.25 mg/kg doxorubicin. These data suggest that downregulating GH signaling may decrease the doxorubicin dose necessary to effectively treat breast cancer.

The influence of growth hormone on bone and adipose programming.

In utero growth hormone exposure is associated with distinct immediate growth responses and long term impacts on adult physiological parameters that include obesity, insulin resistance, and bone function. Growth hormone accelerates cellular proliferation in many tissues but is exemplified by increases in the number of cells within the cartilaginous growth plate of bone. In some cases growth hormone also potentiates differentiation as seen in the differentiation of adipocytes that rapidly fill upon withdrawal of growth hormone. Growth hormone provokes these changes either by direct action or through intermediaries such as insulin-like growth factor-I and other downstream effector molecules. The specific mechanism used by growth hormone in programming tissues is not yet fully characterized and likely represents a multipronged approach involving DNA modification, altered adult hormonal milieu, and the development of an augmented stem cell pool capable of future engagement as is seen in adipose accrual. This review summarizes findings of growth hormone's influence on in utero and neonatal cellular and metabolic profiles related to bone and adipose tissue.

Growth hormone promotes the survival of retinal cells in vivo

Growth hormone (GH) is synthesized and present in the developing chick retina, where it may have local actions in retinal cell differentiation similar to those of conventional growth factors. We have previously shown that retinal GH has neuroprotective effects in retinal ganglion cells. In this paper, we extend our earlier functional studies by examining the in vivo effects of a GH siRNA (NR-cGH-1) after microinjection into the eye cup of the developing chick embryo in ovo. We show that intra-vitreous cGH siRNA lowers both GH mRNA and insulin-like growth factor-1 (IGF-1) mRNA levels in the retina in vivo, and concomitantly elevates the numbers of apoptotic cells in the retina. These effects are apparent 6 h after treatment, and persist for at least 24 h. The apoptotic cells induced by GH withdrawal were primarily located close to the optic fissure of the developing eye, and were distributed in clusters, suggesting that there are sub-populations of retinal cells that are particularly susceptible to apoptotic stimuli. These results support our view that a GH/IGF-1 axis in retinal cells regulates retinal cell survival in vivo.

Melanoma onset after estrogen, thyroid, and growth hormone replacement therapy

Background: Acute sun exposure is the main risk factor for the development of melanoma, especially if associated with a large number of benign melanocytic nevi. Although epidemiologic studies have investigated the effects of exogenous triggers, particularly hormones, our understanding of melanoma is still inadequate. Objective: The aim of this study was to report a case of melanoma that developed after hormonal therapy. Case summary: We report a case of a 26-year-old white woman (weight, 48 kg; Fitzpatrick skin phototype IV; no previous pregnancy) who was referred to the Department of Dermatology, Casa Sollievo della Sofferenza Hospital-IRCCS, San Giovanni Rotondo, Italy, with a malignant melanoma on the left thigh. At the age of 18 years (year 2000), the patient presented with amenorrhea, but no therapy was initiated until 2004. At this time, insufficiency of the gonadal, thyroid, and growth hormone (GH) axes was diagnosed without evidence of hypothalamic-pituitary anatomic damage or of congenital or acquired causes. The patient had an inadequate level of GH (base: 0.8 g/mL; peak: 1.0 ng/mL) during an insulin tolerance test, low levels of thyroid hormones, and a blunted response of luteinizing hormone (base: 0.2 mIU/mL; peak: 10 mIU/mL) and follicle-stimulating hormone (base: 2.6 mIU/mL; peak: 18.5 mIU/mL) to a gonadotrophinreleasing hormone stimulation test. Consequently, replacement therapy with ethinyl estradiol (20 μg) plus progestin (75 μg) (once daily for 21 days/month), levothyroxine (25 μg once daily), and recombinant human GH (0.8 mg SC once daily) was initiated. GH replacement therapy was discontinued after 2 years (June 2006), and thyroid and estrogen replacement therapy were discontinued after 4 years (February 2008). The patient reported first noticing the pigmented lesion 8 months after GH withdrawal, during treatment with the estrogen/progestin combination. Conclusion: We report a case of melanoma onset in a patient who had received hormonal substitutive therapy, where the role of GH therapy alone or in combination with other hormones could not be ruled out.

Impact of Growth Hormone (GH) Deficiency and GH Replacement upon Thymus Function in Adult Patients

BackgroundDespite age-related adipose involution, T cell generation in the thymus (thymopoiesis) is maintained beyond puberty in adults. In rodents, growth hormone (GH), insulin-like growth factor-1 (IGF-1), and GH secretagogues reverse age-related changes in thymus cytoarchitecture and increase thymopoiesis. GH administration also enhances thymic mass and function in HIV-infected patients. Until now, thymic function has not been investigated in adult GH deficiency (AGHD). The objective of this clinical study was to evaluate thymic function in AGHD, as well as the repercussion upon thymopoiesis of GH treatment for restoration of GH/IGF-1 physiological levels.Methodology/Principal FindingsTwenty-two patients with documented AGHD were enrolled in this study. The following parameters were measured: plasma IGF-1 concentrations, signal-joint T-cell receptor excision circle (sjTREC) frequency, and sj/β TREC ratio. Analyses were performed at three time points: firstly on GH treatment at maintenance dose, secondly one month after GH withdrawal, and thirdly one month after GH resumption. After 1-month interruption of GH treatment, both plasma IGF-1 concentrations and sjTREC frequency were decreased (p<0.001). Decreases in IGF-1 and sjTREC levels were correlated (r = 0.61, p<0.01). There was also a decrease in intrathymic T cell proliferation as indicated by the reduced sj/β TREC ratio (p<0.01). One month after reintroduction of GH treatment, IGF-1 concentration and sjTREC frequency regained a level equivalent to the one before GH withdrawal. The sj/β TREC ratio also increased with GH resumption, but did not return to the level measured before GH withdrawal.ConclusionsIn patients with AGHD under GH treatment, GH withdrawal decreases thymic T cell output, as well as intrathymic T cell proliferation. These parameters of thymus function are completely or partially restored one month after GH resumption. These data indicate that the functional integrity of the somatotrope GH/IGF-1 axis is important for the maintenance of a normal thymus function in human adults.Trial RegistrationClinicalTrials.gov NTC00601419

Impact of Growth Hormone (GH) Deficiency and GH Replacement upon Thymus Function in Adult Patients (138.26)

Abstract Context: In rodents, growth hormone (GH), insulin-like growth factor-1 (IGF-1), and GH secretagogues (such as ghrelin) reverse age-related changes in thymus cytoarchitecture and increase thymopoiesis. GH administration also enhances thymic mass and function in HIV-infected patients. Until now, thymic function has not been investigated in adult GH deficiency (AGHD). Objectives: The objective of this clinical study was to evaluate thymic function in AGHD, as well as the repercussion upon thymopoiesis of GH treatment for restoration of GH/IGF-1 physiological levels. Design: Twenty-two patients with documented AGHD were enrolled in this study. The following parameters were measured: plasma IGF-1 concentrations, signal-joint T-cell receptor excision circle (sjTREC) frequency, and sj/ß TREC ratio. Analyses were performed at three time points: firstly on GH treatment at maintenance dose, secondly one month after GH withdrawal, and thirdly one month after GH resumption. Results: After 1-month interruption of GH treatment, both plasma IGF-1 concentrations and sjTREC frequency were significantly decreased. Decreases in IGF-1 and sjTREC levels were significantly correlated. There was also a significant decrease in intrathymic T cell proliferation as indicated by the reduced sj/ß TREC ratio. One month after reintroduction of GH treatment, IGF-1 concentration and sjTREC frequency were restored at the level before arrest of GH treatment. The sj/ß TREC ratio also increased with GH resumption, but did not return to the level measured before GH withdrawal. Conclusions: In patients with AGHD under GH treatment, GH withdrawal decreases thymic T cell output, as well as intrathymic T cell proliferation. These parameters of thymopoiesis are completely or partially restored one month after GH resumption.

Effect of Growth Hormone on Cardiac Contractility in Patients With Adult Onset Growth Hormone Deficiency

This study was conducted to investigate the effect of growth hormone (GH) replacement on cardiac function assessed by standard or tissue Doppler echocardiography in GH deficiency. Ten patients (mean age 47+/-14 years) received GH at a dose of 1.0 IU/day (6 times/week). After 6 months of GH replacement, GH substitution was discontinued. Echocardiography was performed at baseline, after 6 months of therapy, and 1 year after the withdrawal of GH replacement. All parameters were compared with those from 11 healthy controls matched for age, gender, and left ventricular (LV) mass index. After GH replacement, LV ejection fractions were nonsignificantly increased. However, fractional shortening, LV dimensions, and LV volumes did not change. Compared with controls, peak strain (-18.9+/-4.8% vs -15.7+/-6.9%, p<0.01) and strain rate (-1.3+/-0.4/s vs -1.0+/-0.5/s, p<0.01) at baseline were significantly decreased in patients with GH deficiency. Strain and strain rate increased significantly after 6 months of replacement but returned to baseline levels after 12 months off therapy. In conclusion, GH replacement in adult-onset GH deficiency demonstrated beneficial effects on cardiac contractility assessed by strain and strain rate, but these parameters returned to baseline levels after the withdrawal of GH. Strain and strain rate can be used to evaluate subtle changes in myocardium after GH replacement.

Preliminary development of the new individualized HDQoL questionnaire measuring quality of life in adult hypopituitarism

The objectives were (1) to report the preliminary development of the Hormone Deficiency-dependent Quality of Life (HDQoL) questionnaire, a new individualized questionnaire in which respondents rate personally applicable domains for importance and impact of hormonal deficiency and its treatment; (2) to evaluate the HDQoL's psychometric properties for adults with hypopituitarism including growth hormone deficiency (GHD). Internal consistency reliability, aspects of validity, and sensitivity to change of the HDQoL were investigated in: (1) a cross-sectional survey of 157 adults with treated or untreated GHD; (2) a randomized, placebo-controlled study of 3 months' growth hormone (GH) withdrawal from 12 of 21 GH-treated adults. Thirteen of the original 18 HDQoL domains were relevant and important for GH-deficient adults. The shorter 13-item HDQoL had excellent internal reliability (Cronbach's alpha coefficient = 0.914, n = 109), and was sensitive to sex differences (cross-sectional study): women perceived worse present QoL than men [t(149.8) = 2.33, P = 0.021]. The HDQoL was sensitive to change (GH-withdrawal study) with a significant between-group difference in change in domain scores for things I can do physically[t(16) = 2.47, P = 0.025, 2-tailed], patients withdrawn from GH reporting greater negative impact of hormone deficiency on this domain at end-point. Qualitative work resulted in the addition of seven new HDQoL domains, including energy and bodily pain. The HDQoL, although at an early stage of development, proved useful in identifying expected changes following GH withdrawal. The extended 20-item version is recommended for further evaluation in assessing the impact of hypopituitarism on QoL.

P.230 Serum alpha-fetoprotein (AFP) level predicts treatment outcome in chronic hepatitis C (ANRS 1211)

Background: Acute sun exposure is the main risk factor for the development of melanoma, especially if associated with a large number of benign melanocytic nevi. Although epidemiologic studies have investigated the effects of exogenous triggers, particularly hormones, our understanding of melanoma is still inadequate.Objective: The aim of this study was to report a case of melanoma that developed after hormonal therapy.Case summary: We report a case of a 26-year-old white woman (weight, 48 kg; Fitzpatrick skin phototype IV; no previous pregnancy) who was referred to the Department of Dermatology, Casa Sollievo della Sofferenza Hospital-IRCCS, San Giovanni Rotondo, Italy, with a malignant melanoma on the left thigh. At the age of 18 years (year 2000), the patient presented with amenorrhea, but no therapy was initiated until 2004. At this time, insufficiency of the gonadal, thyroid, and growth hormone (GH) axes was diagnosed without evidence of hypothalamic-pituitary anatomic damage or of congenital or acquired causes. The patient had an inadequate level of GH (base: 0.8 g/mL; peak: 1.0 ng/mL) during an insulin tolerance test, low levels of thyroid hormones, and a blunted response of luteinizing hormone (base: 0.2 mIU/mL; peak: 10 mIU/mL) and follicle-stimulating hormone (base: 2.6 mIU/mL; peak: 18.5 mIU/mL) to a gonadotrophinreleasing hormone stimulation test. Consequently, replacement therapy with ethinyl estradiol (20 μg) plus progestin (75 μg) (once daily for 21 days/month), levothyroxine (25 μg once daily), and recombinant human GH (0.8 mg SC once daily) was initiated. GH replacement therapy was discontinued after 2 years (June 2006), and thyroid and estrogen replacement therapy were discontinued after 4 years (February 2008). The patient reported first noticing the pigmented lesion 8 months after GH withdrawal, during treatment with the estrogen/progestin combination.Conclusion: We report a case of melanoma onset in a patient who had received hormonal substitutive therapy, where the role of GH therapy alone or in combination with other hormones could not be ruled out.

Common Carotid Intima-Media Thickness in Growth Hormone (GH)-Deficient Adolescents: A Prospective Study after GH Withdrawal and Restarting GH Replacement

We prospectively investigated the risk of early atherosclerosis, by classical cardiovascular risk factors and intima-media thickness (IMT) at the common carotid arteries, in 23 adolescents diagnosed as GH deficient (GHD) during childhood and in 23 healthy sex-, age-, and BMI-matched controls. Measurements were performed in all subjects before stopping GH replacement. Because the diagnosis of GHD had been confirmed in 15 of the 23 adolescents, the protocol changed according to the diagnosis as follows: measurements were repeated after 6 months of GH withdrawal and 6 months of GH reinstitution in the 15 with GHD, and after 6 and 12 months of GH withdrawal, measurements were also taken in the eight non-GHD subjects. Serum IGF-I levels were in the normal range for age in all patients before GH withdrawal. When compared with controls, before GH withdrawal, GHD adolescents had reduced high-density lipoprotein cholesterol levels and increased total/high-density lipoprotein cholesterol ratio, fibrinogen, low-density lipoprotein cholesterol, and glucose levels; non-GHD adolescents had increased glucose, insulin, and homeostasis model assessment score. IMT at the common carotid arteries was similar in GHD and controls (0.52 +/- 0.03 vs. 0.55 +/- 0.06 mm; P = 0.23) and was higher in non-GHD than in controls (0.62 +/- 0.03 vs. 0.54 +/- 0.06 mm; P = 0.01). In GHD adolescents, 6 months of GH treatment withdrawal and 6 months of GH treatment reinstitution modified IGF-I levels, lipid profile, and insulin resistance but not IMT or systolic and diastolic peak velocities at the common carotid arteries. In non-GHD subjects, 12 months of GH treatment withdrawal significantly decreased IGF-I levels, IMT (to 0.54 +/- 0.06 mm; P < 0.001 vs. baseline), systolic and diastolic peak velocities, and improved insulin resistance. In conclusion, the discontinuation of GH in confirmed GHD adolescents is not followed by significant alterations of the common carotid arteries, despite the profound negative alterations of the lipid profile. In adolescents who were not confirmed to have GHD, IMT was increased while on GH therapy and normalized when they were taken off of GH.

Short-Term Effects of Growth Hormone (GH) Treatment or Deprivation on Cardiovascular Risk Parameters and Intima-Media Thickness at Carotid Arteries in Patients with Severe GH Deficiency

To explore early effects of GH treatment or deprivation on cardiovascular risk factors and carotid intima-media thickness (IMT), we designed this randomized, cross-over study in 34 adult patients with severe GH deficiency. At study entry, the patients were randomized into two groups (A and B); group A (n = 17) received appropriate replacement therapy including GH at standard doses for 6 months and then were withdrawn from GH for the subsequent 6 months; group B (n = 17) received appropriate replacement therapy excluding GH for 6 months with the addition of GH in the subsequent 6 months. After the first 6 months, we observed a significant increase in IGF-I levels and of high-density lipoprotein (HDL)-cholesterol together with a significant decrease in diastolic blood pressure, the total/HDL-cholesterol ratio, and C-reactive protein in the patients in group A, whereas vascular parameters did not significantly change. In the patients in group B, none of the parameters studied significantly changed. After 6 months of GH withdrawal in the patients in group A, a significant decrease in IGF-I levels, a significant increase in the total/HDL-cholesterol ratio and C-reactive protein, and a trend toward an impairment of carotid IMT and peak velocities were observed. In the patients in group B, the addition of GH to the standard replacement induced a significant increase in IGF-I levels together with a decrease in systolic and diastolic blood pressure, total cholesterol and total/HDL-cholesterol ratio, and C-reactive protein, and an increase in HDL-cholesterol levels with a trend toward an improvement of vascular parameters. At the end of the study, mean IMT was significantly lower than at baseline both in group A (from 0.88 +/- 0.28 to 0.85 +/- 0.27 mm, P = 0.0003) and in group B (from 0.83 +/- 0.21 to 0.80 +/- 0.20 mm, P = 0.003). In conclusion, 6 months of GH replacement has beneficial effects whereas 6 months of GH deprivation has detrimental effects on cardiovascular risk factors and atherosclerosis. These findings support the indication for GH replacement in severe GH deficiency adult patients.

Evidence that sensitivity to growth hormone (GH) is growth period and tissue type dependent: studies in GH-deficient lit/lit mice.

We previously found that the magnitude of skeletal deficits caused by GH deficiency varied during different growth periods. To test the hypothesis that the sensitivity to GH is growth period dependent, we treated GH-deficient lit/lit mice with GH (4 mg/kg body weight.d) or vehicle during the prepubertal and pubertal (d 7-34), pubertal (d 23-34), postpubertal (d 42-55), and adult (d 204-217) periods and evaluated GH effects on the musculoskeletal system by dual energy x-ray absorptiometry (DEXA) and peripheral quantitative computed tomography. GH treatment during different periods significantly increased total body bone mineral content, bone mineral density (BMD), bone area, and lean body mass and decreased percentage of fat compared with vehicle; however, the magnitude of change varied markedly depending on the treatment period. For example, the increase in total body BMD was significantly (P < 0.01) greater when GH was administered between d 42-55 (15%) compared with pubertal (8%) or adult (7.7%) periods, whereas the net loss in percentage of body fat was greatest (-56%) when GH was administered between d 204 and 216 and least (-27%) when GH was administered between d 7 and 35. To determine whether GH-induced anabolic effects on the musculoskeletal system are maintained after GH withdrawal, we performed DEXA measurements 3-7 wk after stopping GH treatment. The increases in total body bone mineral content, BMD, and lean body mass, but not the decrease in body fat, were sustained after GH withdrawal. Our findings demonstrate that the sensitivity to GH in target tissues is growth period and tissue type dependent and that continuous GH treatment is necessary to maintain body fat loss but not BMD gain during a 3-7 wk follow-up.

Responses of Markers of Bone and Collagen Turnover to Exercise, Growth Hormone (GH) Administration, and GH Withdrawal in Trained Adult Males1

To examine the interactions between acute exercise and GH on markers of bone and collagen turnover and to assess the potential for detecting GH abuse in athletes using these markers, we studied 17 aerobically trained males (age, 26.9+/-1.5 yr). Sequential studies of exercise, GH administration, and GH withdrawal were undertaken. A randomized, controlled study of rest vs. exercise showed that exercise did not change serum osteocalcin; other markers of formation increased transiently (each P<0.001): bone-specific alkaline phosphatase (+16.1%), carboxyterminal propeptide of type I procollagen (+14.1%), and procollagen III N-terminal extension peptide (+5.0%). The carboxyterminal cross-linked telopeptide of type I collagen, a bone resorption marker, increased 9.7% (P = 0.018) in response to exercise. A randomized, double blind, placebo-controlled, parallel study of recombinant human GH treatment (0.15 IU/kg x day) for 1 week increased serum osteocalcin (net increase preexercise, +/-10.0%; P = 0.017), carboxyterminal propeptide of type I procollagen (+17.6%; P = 0.002), procollagen III N-terminal extension peptide (+48.4%; P = 0.001), and carboxyterminal cross-linked telopeptide of type I collagen (53.3%; P = 0.009). Disappearance half-times after cessation of recombinant human GH for pre- and postexercise markers ranged from 248-770 h. We conclude 1) endurance exercise transiently activates bone and collagen turnover; 2) brief GH administration results in similar but quantitatively greater augmentation; and 3) these data will assist in designing a GH detection strategy.

Responses of Markers of Bone and Collagen Turnover to Exercise, Growth Hormone (GH) Administration, and GH Withdrawal in Trained Adult Males

Responses of Markers of Bone and Collagen Turnover to Exercise, Growth Hormone (GH) Administration, and GH Withdrawal in Trained Adult Males

Responses of the growth hormone (GH) and insulin-like growth factor axis to exercise, GH administration, and GH withdrawal in trained adult males: a potential test for GH abuse in sport.

GH abuse by elite athletes is currently undetectable. To define suitable markers of GH doping, we assessed the effects of acute exercise, GH administration, and GH withdrawal on the GH/insulin-like growth factor (IGF) axis in athletic adult males. Acute endurance-type exercise increased serum GH, GH-binding protein (GHBP), total IGF-I, IGF-binding protein (IGFBP)-3, and acid-labile subunit (ALS), each peaking at the end of exercise. IGFBP-1 increased after exercise was completed. Free IGF-I did not change with exercise. Recombinant human GH treatment (0.15 IU/kg x day) for 1 week increased serum total IGF-I, IGFBP-3, and ALS, exaggerating the responses to exercise. IGFBP-2 and IGFBP-1 were trivially suppressed. After GH withdrawal, the GH response to identical exercise was suppressed. Total IGF-I, IGFBP-3, and ALS returned to baseline over 3-4 days. In summary, 1) acute exercise transiently increased all components of the IGF-I ternary complex, possibly due to mobilization of preformed intact complexes; 2) GH pretreatment augmented the exercise-induced changes in ternary complexes; 3) postexercise IGFBP-1 increments may protect against delayed onset hypoglycemia; 4) serum total IGF-I, IGFBP-3, and ALS may be suitable markers of GH abuse; and 5) differences in disappearance times altered the sensitivity of each marker for detecting GH abuse.

Responses of the Growth Hormone (GH) and Insulin-Like Growth Factor Axis to Exercise, GH Administration, and GH Withdrawal in Trained Adult Males: A Potential Test for GH Abuse in Sport

Responses of the Growth Hormone (GH) and Insulin-Like Growth Factor Axis to Exercise, GH Administration, and GH Withdrawal in Trained Adult Males: A Potential Test for GH Abuse in Sport

Unfavourable impact of growth hormone (GH) discontinuation on body composition and cholesterol profiles after the completion of height growth in GH-deficient young adults.

Growth hormone (GH) plays an important role in the regulation of body composition and metabolism. GH deficiency is associated with obesity and hypercholesterolemia, which respond to GH treatment. In this study we evaluated changes in body composition and cholesterol profiles after discontinuation of GH therapy to assess atherogenic risk factors in GH-deficient patients. We studied 18 male patients with GH deficiency 17-20 years of age at the time of discontinuing GH therapy. Body composition and cholesterol were measured 6 months before discontinuation of GH therapy with a weekly dose of 0.5 IU/kg (approximately 0.19 mg/kg), and immediately, 2 months, and 6 months after the end of GH therapy. Two months after termination of GH therapy the percentage of body fat and fat mass increased from 7.4% to 9.4% and from 3.8 kg to 5.0 kg, respectively, and remained high thereafter. Lean body mass decreased gradually, but the change was not significant. Lean body mass: fat mass ratio decreased from 14.7 at termination of GH therapy to 10.9 at the end of study. Total cholesterol (TC) showed a significant linear increase from 156 mg/dl immediately after discontinuation to 169 mg/dl 6 months after discontinuation of GH, whereas high-density lipoprotein cholesterol (HDLC) showed no change during the study. The TC to HDLC ratio showed a slight but insignificant trend toward an increase. There were no significant changes in any variables during the last 6 months of GH therapy. GH therapy in patients with GH deficiency can reduce risk factors for obesity-related diseases and atherosclerosis. These beneficial effects are reversed after discontinuation of GH therapy. Further long-term studies of the effects of the GH withdrawal on lipid profiles, adiposity and life expectancy must be performed.

Growth hormone (GH) deficiency (GHD) of childhood onset: reassessment of GH status and evaluation of the predictive criteria for permanent GHD in young adults.

GH secretion was reevaluated after completion of GH treatment at a mean age of 19.2 +/- 3.2 yr in 35 young adults with childhood-onset GH deficiency (GHD). The patients were subdivided into 4 groups according to their first pituitary magnetic resonance imaging (MRI) findings: group I, 11 patients with isolated GHD (IGHD) and normal pituitary volume (280 +/- 59.4 mm3); group II, 7 patients with IGHD and small pituitary gland (163.1 +/- 24.4 mm3; P = 0.0009 vs. group I); group III, 13 patients (5 with IGHD and 8 with multiple pituitary hormone deficiency) with congenital hypothalamic-pituitary abnormalities such as pituitary hypoplasia (95.8 +/- 39.3 mm3; P < 0.00001 vs. group I and P = 0.003 vs. group II), pituitary stalk agenesis, and posterior pituitary ectopia; and group IV, 4 patients with multiple pituitary hormone deficiency secondary to craniopharyngioma. Pituitary MRI and GH secretory status were reevaluated after GH withdrawal using arginine, insulin induced-hypoglycemia, and sequential arginine-insulin tests. Serum insulin-like growth factor I (IGF-I) and IGF-binding protein-3 (IGFBP-3) were determined at the time of retesting and 6, 12, and 24 months after discontinuation of treatment in the patients with permanent GHD and after 6 months in those with normal GH responses to stimulation. The patients in groups I and II showed a normal response to stimulation after completion of GH treatment regardless of pituitary size, whereas all patients in groups III and IV still had a GH response of less than 3 microg/L to any of the tests. Pituitary volume normalized in 6 of 7 patients in group II, whereas in all patients in group III MRI studies confirmed the initial findings. Mean IGF-I and IGFBP-3 concentrations at the time of retesting were significantly higher in groups I and II than in groups III and IV. In patients of groups III and IV, mean IGF-I was significantly decreased after 6 and 12 months, whereas IGFBP-3 was significantly decreased 12 months after treatment withdrawal. Our results confirm that a high proportion of children with IGHD and normal or small pituitary show normalization of GH secretion at the completion of GH treatment, whereas GHD is permanent in all patients with pituitary hypoplasia, pituitary stalk agenesis, and posterior pituitary ectopia. IGF-I and IGFBP-3 determinations shortly after GH withdrawal had limited value in the diagnosis of GHD of childhood onset associated with congenital hypothalamic-pituitary abnormalities, but became accurate after 6-12 months. We suggest that patients with GHD and congenital hypothalamic-pituitary abnormalities do not require further investigation of GH secretion, whereas patients with IGHD and normal or small pituitary gland should be retested well before the attainment of adult height.